Liquid-cooled crankcase for an internal combustion engine

Abstract

The invention relates to a cylinder head (1) and a crankcase (2) of an internal combustion engine with a coolant flow that runs parallel through the cylinder head (1) and the crankcase (2).

Description

The invention relates to a liquid-cooled crankcase for an internal combustion engine and to an internal combustion engine having the same crankcase.DE 10 2009 023 530 A1 discloses a liquid-cooled internal combustion engine having a crankcase and a cylinder head, which have a coolant jacket that can be passed through together. The internal combustion engine has at least two cylinders, between which a web is formed. The coolant jacket extends on a first and a second longitudinal side in the crankcase substantially equidistantly along the cylinders and from the coolant jacket in the first longitudinal side further into the cylinder head and in the cylinder head corresponding to a substantial transverse flow and further into the coolant jacket in the second longitudinal side. A coolant can be fed into the coolant jacket in the first longitudinal side and can be discharged from the coolant jacket in the second longitudinal side. Furthermore, a coolant feed channel is provided, which extends substantially along the coolant jacket in the first longitudinal side, wherein a feed channel is provided from the coolant feed channel into the coolant channel in the first longitudinal side, which opens in a gusset region of the web from geodetically at the bottom into the coolant channel in the first longitudinal side.As further prior art, reference is made to EP 3 379 063 A1, DE 103 31 918 A1, U.S. Pat. No. 6,481,392 B1, WO 2015 / 086 791 A1, CN 1 07 956 590 A and CN 1 03 485 921 A.EP 2 132 423 B1 discloses a liquid-cooled internal combustion engine which comprises, inter alia, a cylinder head and a crankcase. The cooling water is supplied to the internal combustion engine via a coolant distributor strip and from there reaches a coolant inlet in the crankcase at the individual cylinders of the internal combustion engine. There, the cooling water stream is divided into a first cooling water stream and a second cooling water stream. The first cooling water stream flows from the coolant inlet in the crankcase first upward into the cylinder head and then leaves the cylinder head again through a coolant outlet which is located in the cylinder head. The second coolant flow, on the other hand, flows from the coolant inlet in the crankcase first into a cooling jacket of the crankcase and then upwards into the cylinder head, in order then finally to leave the cylinder head again through the coolant outlet which is located in the cylinder head.A disadvantage of this coolant guidance is the fact that the cylinder head is partially cooled by cooling water which has already been heated beforehand in the cooling jacket of the crankcase. Therefore, relatively high temperatures can arise in the cylinder head during operation, which is undesirable. This applies in particular to the connecting web in the cylinder head between two adjacent outlet bores in the cylinder head.The invention is therefore based on the object of improving the cooling in such an internal combustion engine.This object is achieved by a crankcase according to claim 1 and an internal combustion engine according to claim 2.The internal combustion engine according to the invention has a crankcase according to the invention and a cylinder head.The cylinder head is used for mounting on the crankcase of the internal combustion engine, wherein it is preferably a V-engine, i.e. a piston engine having a plurality of cylinders which are divided into two cylinder banks which are angled with respect to one another in a V-shape.The cylinder head first has, in accordance with the prior art, a so-called fire deck on the underside of the cylinder head in order to separate the cylinder head from the crankcase of the internal combustion engine and the combustion chamber.Further, the cylinder head according to the related art has a mounting surface on the lower side of the cylinder head for mounting the cylinder head on the crankcase of the internal combustion engine.In the mounting surface of the cylinder head, according to the prior art, a coolant inlet is provided to receive the coolant (e.g., cooling water) from the crankcase of the internal combustion engine.The cylinder head has an upper cooling sub-chamber and a lower cooling sub-chamber which are separated from one another by an intermediate deck.The coolant flows here from the coolant inlet in the mounting surface of the cylinder head through a riser duct upwards into the upper cooling sub-chamber. Subsequently, the coolant flows from the upper cooling sub-space downward into the lower cooling sub-space through a connecting channel in the intermediate deck.In this respect, the cylinder head corresponds substantially to the known cylinder head described at the beginning according to EP 2 132 423 B1.The cylinder head differs from this known cylinder head in that the coolant outlet is likewise located in the mounting surface of the cylinder head, so that the coolant heated in the cylinder head flows out of the cylinder head through the coolant outlet downward into the crankcase. The cylinder head thus receives the cold coolant from the crankcase via the coolant inlet in the mounting surface of the cylinder head and then releases the heated coolant to the crankcase via the coolant outlet in the mounting surface of the cylinder head. This allows a completely parallel coolant to be guided through the cylinder head on the one hand and through the crankcase on the other hand. In contrast, the common coolant outlet of cylinder head and crankcase in the known internal combustion engine described at the beginning according to EP 2 132 423 B1 is located laterally in the cylinder head.The parallel coolant guidance enables a reduction in the pressure loss and in particular reduces the maximum temperature of the connecting web between the adjacent outlet bores in the cylinder head. This reduces the tendency to form cracks in the cylinder head.In a preferred embodiment, the cylinder head includes a mounting bore that may receive, for example, an injector for injecting fuel or a spark plug. Such mounting bores are known per se from the prior art and are also shown, for example, in the aforementioned patent specification EP 2 132 423 B1. This mounting bore passes in the cylinder head through the upper cooling sub-chamber, the intermediate deck, the lower cooling sub-chamber and the fire deck. The connecting channel provided according to the invention between the upper cooling sub-chamber and the lower cooling sub-chamber can laterally surround the mounting bore.For example, the connecting channel between the upper cooling sub-chamber and the lower cooling sub-chamber can consist of a plurality of cooling sub-channels through which the coolant flows in parallel. In this case, the partial channels are preferably arranged distributed over the circumference of the mounting bore, and more specifically preferably equidistantly.The individual partial channels can have the same cross section. Preferably, however, the sub-channels have different cross-sections, wherein the cross-sections of the individual sub-channels are preferably adapted such that an optimum cooling effect is achieved.There are various possibilities with regard to the number of subchannels. For example, a partial channel can be arranged in each valve land. However, the invention is not limited to a specific number with respect to the number of subchannels.In the preferred exemplary embodiments, the cylinder head has a plurality of (e.g. two) through-bores for inlet ducts in order to fill the combustion chamber of the internal combustion engine before a combustion process. Furthermore, the cylinder head preferably has a plurality of (e.g. two) through-bores for outlet ducts in order to exhaust the combustion chamber of the internal combustion engine after a combustion process. The internal combustion engine therefore preferably comprises two inlet valves and two outlet valves. The through-bores for the inlet channels and the outlet channels are preferably arranged distributed around the mounting bore, in particular equidistantly to the mounting bore and equidistantly in the circumferential direction. The individual sub-channels of the connecting channel between the upper cooling sub-space and the lower cooling sub-space are then preferably each arranged in a central angular position between two adjacent through-holes.The above description relates only to the configuration of the cylinder head. However, the invention also claims independent protection for a correspondingly adapted crankcase.Thus, the crankcase according to the invention firstly provides, in accordance with the prior art, an upper mounting surface in order to be able to connect the crankcase to the cylinder head.In the crankcase, at least one cylinder is located for slidably receiving a piston. According to the invention, however, a plurality of cylinders are provided, for example 2, 4, 6, 8 or 12 cylinders, which can be arranged optionally in rows or V-shaped fashion.Furthermore, in the crankcase according to the prior art, a cooling jacket is provided for passing the coolant through, wherein the cooling jacket forms the cylinder at least partially in the shape of a jacket.In the upper mounting surface of the crankcase there is at least one first coolant bore for passing the coolant through, as is also known from the patent specification EP 2 132 423 B1 already cited at the beginning.Furthermore, the crankcase according to the invention has, in accordance with the prior art, a coolant inlet for supplying the cold coolant into the crankcase, wherein the coolant inlet in the crankcase branches off to the first coolant bore in the upper mounting surface on the one hand and to the cooling jacket on the other hand, so that the coolant flowing in through the coolant inlet flows partially upward into the cylinder head and partially into the cooling jacket of the crankcase.In addition, the crankcase according to the invention has a coolant outlet in order to discharge the heated coolant from the crankcase.In this respect, the crankcase according to the invention corresponds to the known crankcase according to EP 2 132 423 B1 described at the beginning.The crankcase according to the invention is characterized in that a second coolant bore is provided in the upper mounting surface of the crankcase in order to receive the coolant from the cylinder head again. The second coolant bore in the upper mounting surface of the crankcase thus serves to return the coolant heated in the cylinder head back into the crankcase.In addition, the crankcase according to the invention is characterized in that the second coolant bore in the mounting surface is connected to the coolant outlet, so that the coolant heated in the cylinder head flows through the second coolant bore into the crankcase and leaves the crankcase through the coolant outlet. In contrast to the known internal combustion engine described at the beginning according to EP 2 132 423 B1, the heated coolant thus leaves the internal combustion engines not via a coolant outlet in the cylinder head, but rather via a coolant outlet in the crankcase.Furthermore, the crankcase according to the invention is characterized in that the coolant outlet is not arranged in the upper mounting surface of the crankcase, so that the heated coolant is not discharged into the cylinder head.As already briefly mentioned above, this ensures that the coolant flows through the cylinder head on the one hand and the crankcase on the other hand in parallel. In the internal combustion engine according to the invention, therefore, neither cylinder head nor crankcase are cooled by coolant which has already been heated beforehand in the respective other component (cylinder head or crankcase).According to the invention, the crankcase has a plurality of cylinders each with a cooling jacket. As in EP 2 132 423 B1, a coolant distributor strip is provided which receives the cold coolant from the coolant inlet and distributes it to the cooling jackets of the individual cylinders and to the cylinder head. In addition, a collecting channel is provided which receives the heated coolant from the cooling jackets of the individual cylinders and from the cylinder head and conducts it to the coolant outlet.Finally, it should be mentioned that the invention not only claims independent protection for the crankcase according to the invention. Rather, the invention also claims protection for an internal combustion engine having a corresponding cylinder head and a crankcase according to the invention.Other advantageous refinements of the invention are characterized in the dependent claims or are explained in more detail below together with the description of the preferred exemplary embodiment of the invention on the basis of the figures. The following are shown: FIG. 1 shows a schematic illustration of an internal combustion engine according to the invention for illustrating the coolant flows in the internal combustion engine, FIG. 2 is a cross-sectional view through an internal combustion engine according to the invention, FIG. 3 is another cross-sectional view of the internal combustion engine of FIG. 2; and FIG. 4 is a cross-sectional view through the cylinder head in the region of an upper cooling chamber portion.FIG. 1 shows a schematic illustration of an internal combustion engine according to the invention for illustrating the coolant flows in the internal combustion engine. The internal combustion engine partially corresponds to the internal combustion engine according to the patent specification EP 2 132 423 B1 cited at the beginning, so that reference can be made to this earlier patent specification for the details.The internal combustion engine according to the invention has a cylinder head 1 and a crankcase 2, wherein cooling water flows in parallel through the cylinder head 1 on the one hand and through the crankcase 2 on the other hand for cooling the internal combustion engine, as will be described in detail below.The cylinder head 1 has a fire deck 3 on its underside, which forms a mounting surface 4 with its underside in order to mount the cylinder head 1 on the crankcase 2.In the cylinder head 1 there are an upper cooling sub-chamber 5 and a lower cooling sub-chamber 6, which are separated from one another by an intermediate deck 7, wherein in the intermediate deck 7 there is a connecting duct 8 which allows a coolant flow from the upper cooling sub-chamber 5 into the lower cooling sub-chamber 6, as will be described in more detail below.In the lower mounting surface 4 of the cylinder head 1 there is a coolant inlet 9 for receiving cold cooling water from the crankcase 2.The cold cooling water then flows in the cylinder head 1 starting from the coolant inlet 9 first through a riser duct 10 into the upper cooling sub-chamber 5 of the cylinder head 1. from there the coolant then flows through the connecting duct 8 into the lower cooling sub-chamber 6 of the cylinder head 1.The cylinder head 1 thus receives the cold cooling water from the crankcase 2 and then releases the heated cooling water again to the crankcase 2, which enables a parallel coolant flow through the cylinder head 1 on the one hand and through the crankcase 2 on the other hand.The crankcase 2 first has a cylinder 12 in which a piston, not shown, is displaceably guided, as is sufficiently known from reciprocating piston engines.The cylinder 12 is surrounded annularly by a cooling jacket 13 in order to cool the crankcase 2, in particular in the region of the cylinder 12.The cold coolant flows via a coolant inlet 14 into the crankcase 2 here.The first coolant flow flows initially upward from the coolant inlet 14 of the crankcase 2 and enters the cylinder head 1 there through a coolant bore 15 in an upper mounting surface 16 of the crankcase 2.The second coolant flow, on the other hand, flows from the coolant inlet 14 of the crankcase 2 into the cooling jacket 13 of the crankcase 2 in order to cool the cylinder 12.Furthermore, the crankcase 2 has a further coolant bore 17 in the upper mounting surface 16, in order to return the coolant heated in the cylinder head 1 back into the crankcase 2.Finally, the crankcase 2 comprises a coolant outlet 18 in order to discharge the coolant from the internal combustion engine again.In the coolant guidance according to the invention described above, the coolant flows through the cylinder head 1 on the one hand and the crankcase 2 on the other hand, i.e. in parallel. This offers the advantage that neither the cylinder head 1 nor the crankcase 2 has to be cooled by coolant which has already been heated beforehand in the respective other component (cylinder head 1 or crankcase 2). This substantially improves the cooling of the internal combustion engine.FIGS. 2 and 3 show different sectional views of the internal combustion engine according to the invention described above, wherein reference is made to the above description in order to avoid repetitions.It can additionally be seen from FIG. 2 that the cylinder head 1 has a mounting bore 19 coaxial to the cylinder 12, which mounting bore can accommodate, for example, an injector or a spark plug.The mounting bore 19 passes through the upper cooling sub-chamber 5, the intermediate deck 7, the lower cooling sub-chamber 6 and the fire deck 3.The connecting channel 8 between the upper cooling sub-chamber 5 and the lower cooling sub-chamber 6 consists here of a plurality of cooling sub-channels 8.1, 8.2 (see FIG. 4 ) which are distributed around the mounting bore 19, namely equidistantly with respect to one another and equidistantly with respect to the mounting bore 19.The invention is not limited to the preferred embodiment of the invention described above. Rather, a large number of variants and modifications are possible, which likewise make use of the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and the features of the subclaims independently of the claims respectively referred to and in particular also without the features of the main claim. The invention also encompasses various aspects of the invention that enjoy protection independently of one another.List of reference characters1 Cylinder head 2 Crankcase 3 Fire deck 4 Mounting surface of the cylinder head 5 Upper cooling sub-chamber in the cylinder head 6 Lower cooling sub-chamber in the cylinder head 7 Intermediate deck between the upper and the lower cooling sub-chamber 8 Connecting duct between upper and lower cooling sub-chamber 8.1, 8.2 Connecting duct 9 Coolant inlet of the cylinder head 10 Riser duct in the cylinder head 11 Coolant outlet of the cylinder head 12 Cylinder 13 Cooling jacket of the crankcase 14 Coolant inlet of the crankcase 15 Coolant bore in the mounting surface of the crankcase 16 Mounting surface of the crankcase 17 Coolant bore in the mounting surface of the crankcase 18 Coolant outlet of the crankcase 19 Mounting bore for injector or spark plug

Claims

Crankcase (2) for mounting under a cylinder head (1) of an internal combustion engine, in particular a V-engine, having: a) an upper mounting surface (16) for mechanical connection to the cylinder head (1), b) at least one cylinder (12) for displaceably receiving a piston, c) a cooling jacket (13) for passing a coolant through, wherein the cooling jacket (13) surrounds the cylinder (12) at least partially in the form of a jacket, namely annularly, d) a first coolant bore (15) in the upper mounting surface (16) for passing the coolant through to the cylinder head (1), e) a coolant inlet (14) for supplying the coolant into the crankcase (2), wherein the coolant inlet (14) branches to the first coolant bore (15) in the upper mounting surface (16) on the one hand and to the cooling jacket (13) on the other hand, such that the coolant flowing in through the coolant inlet (14) divides into a first coolant flow and a second coolant flow, wherein the first coolant flow flows from the coolant inlet (14) to the coolant bore (15) in the upper mounting surface (16) and the second coolant flow flows from the coolant inlet (14) into the cooling jacket (13) of the crankcase (2), and f) a coolant outlet (18) for discharging the coolant, wherein: g) a second coolant bore (17) is provided in the upper mounting surface (16) of the crankcase (2) in order to receive the coolant again from the cylinder head (1), h) the second coolant bore (17) in the upper mounting surface (16) is connected to the coolant outlet (18), such that the coolant heated in the cylinder head (1) flows through the second coolant bore (17) into the crankcase (2) and leaves the crankcase (2) through the coolant outlet (18), and i) the coolant outlet (18) is not arranged in the upper mounting surface (16), such that the heated coolant is not discharged into the cylinder head (1), characterized by: j) a plurality of cylinders (12) each having a cooling jacket (13), k) a coolant distribution strip which receives cold coolant from the coolant inlet (14) and distributes it to the cooling jackets (13) of the individual cylinders (12) and to the cylinder head (1), and I) a collecting duct which receives heated coolant from the cooling jackets (13) of the individual cylinders (12) and from the cylinder head (1) and conducts it to the coolant outlet (18).Internal combustion engine, in particular as a V-engine, having - a crankcase (2) according to Claim 1; and - a cylinder head (1) for mounting on a crankcase (2) of an internal combustion engine, in particular a V-engine, having: a) a fire deck (3) on an underside of the cylinder head (1) for separating the cylinder head (1) from the crankcase (2) of the internal combustion engine, b) a mounting surface (4) on the underside of the cylinder head (1) for mounting the cylinder head (1) on the crankcase (2) of the internal combustion engine, c) a coolant inlet (9) in the mounting surface (4) of the cylinder head (1) for receiving coolant from the crankcase (2) of the internal combustion engine, d) an upper cooling sub-chamber (5) for passing the coolant through, e) a riser duct (10), which connects the coolant inlet (9) in the mounting surface (4) to the upper cooling sub-space (5) so that the coolant flows out of the coolant inlet (9) in the mounting surface (4) first into the upper cooling sub-space (5), f) a lower cooling sub-space (6) for the passage of the coolant, g) an intermediate deck (7) which separates the upper cooling sub-space (5) from the lower cooling sub-space (6), h) a connecting duct (8; 8.1, 8.2) in the intermediate deck (7) so that the coolant flows through the connecting duct (8; 8.1, 8.2) flows from the upper cooling sub-chamber (5) into the lower cooling sub-chamber (6), and i) a coolant outlet (11) for discharging the coolant after flowing through the cylinder head (1), j) wherein the coolant outlet (11) is likewise arranged in the mounting surface (4) of the cylinder head (1), so that coolant heated in the cylinder head (1) flows from the cylinder head (1) through the coolant outlet (11) downward into the crankcase (2).Internal combustion engine according to Claim 2, characterized in that the cylinder head (1) contains a mounting bore (19) for receiving a spark plug or an injector for injecting fuel into a combustion chamber of the internal combustion engine, b) in that the mounting bore (19) passes through the upper cooling sub-chamber (5), the intermediate deck (7), the lower cooling sub-chamber (6) and the firing deck (3), and c) in that the connecting duct (8; 8.1, 8.2) between the upper cooling sub-chamber (5) and the lower cooling sub-chamber (6) surrounds the mounting bore (19).Internal combustion engine according to Claim 3, characterized in that the connecting duct (8; 8.1, 8.2) consists of a plurality of sub-ducts (8.1, 8.2) through which the coolant flows, and b) in that the sub-ducts (8.1, 8.2) are distributed, in particular equidistantly, over the circumference of the mounting bore (19).Internal combustion engine according to Claim 4, characterized in that a) in that the cylinder head (1) has a plurality of, in particular two, through-bores for inlet ducts in order to fill the combustion chamber of the internal combustion engine before a combustion process, b) in that the cylinder head (1) has a plurality of, in particular two, through-bores for outlet ducts in order to empty the combustion chamber of the internal combustion engine after a combustion process, c) in that the through-bores for the inlet ducts and the outlet ducts are arranged distributed around the mounting bore (19), in particular equidistantly with respect to the mounting bore (19) and equidistantly in the circumferential direction, d) in that the sub-ducts (8.1, 8.2) of the connecting duct (8; 8.1, 8.2) are each arranged in a central angular position between two adjacent through-bores.

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